In conventional solvent refined coal reactors, the amount of completion of the reaction in the reactor for desulfurization and hydrogenation is limited because the reactor is backmixed. If attempts are made to rectify this problem by subdividing the reactor into compartments, the temperature rise in each compartment becomes excessive because the reaction in each compartment is highly exothermic. To prevent the reaction from running away, some means must be provided to control the reaction. A need has, therefore, arisen for providing this control so that the reaction can be carried out in a more efficient manner than has been available up to the present time.